Variable Ratio Steering
PerformanceAverage price
800€ - 2500€
Variable ratio steering, also known as active or dynamic steering, is a sophisticated chassis system that continuously optimizes the ratio between the steering wheel movement and the steering angle of the wheels. Unlike a standard steering system where this ratio is fixed, this technology adjusts it based on vehicle speed, the selected driving mode, and sometimes even the yaw rate. At low speeds, for city maneuvers or parking, the system makes the steering very direct: a small turn of the steering wheel results in a large wheel angle, which greatly facilitates maneuvers and reduces driver fatigue. Conversely, at high speeds on the highway, the steering becomes more indirect. A larger steering wheel movement is then required for the same steering angle, ensuring excellent straight-line stability, filtering out unintentional micro-corrections, and providing an enhanced sense of security. Controlled by an electronic control unit (ECU), this system uses an electric actuator, often coupled with a planetary gear set on the steering column, to add or subtract steering angle relative to the driver's input. It is a key component linking performance, comfort, and active safety.
Benefits
- ✓Increased maneuverability at low speeds, facilitating parking and city driving.
- ✓Improved stability and safety at high speeds, reducing vehicle nervousness.
- ✓Optimized driving comfort by reducing steering effort and the number of steering wheel turns.
- ✓Increased responsiveness and precision during dynamic or sporty driving.
Learn more
What is variable ratio steering?
Variable ratio steering represents a major advancement over traditional power steering systems. While a conventional steering system maintains a fixed ratio between the steering wheel's rotation angle and the wheels' steering angle (for example, 15:1), variable steering adjusts this ratio in real time. The system aims to solve a fundamental dilemma: a very direct steering is ideal for low-speed agility, but it can make the car twitchy and unstable at high speeds. Conversely, an indirect steering is reassuring on the highway but impractical for parallel parking. Variable steering offers the best of both worlds by adapting its response to every situation.
How does this technology work?
The operation of variable ratio steering relies on the addition of an intelligent mechanism between the steering wheel and the steering rack. The most common solution, popularized by brands like BMW with its "Active Steering", integrates a planetary gear set (or epicyclic gear train) into the steering column. An electric motor, controlled by an electronic control unit (ECU), acts on this gearing. Depending on the information received (vehicle speed, steering wheel angle, etc.), the motor can:
- At low speed: Add rotation angle. The driver turns the steering wheel by 90 degrees, but the system adds 30, transmitting a total of 120 degrees to the rack. The wheels turn more, for less steering wheel effort.
- At high speed: Subtract rotation angle. The driver turns the steering wheel by 10 degrees, but the system subtracts 3. The rack receives only 7 degrees. The steering is less sensitive, which prevents abrupt course deviations.
This ECU continuously analyzes data to provide a smooth and imperceptible transition for the driver, ensuring an always-appropriate response.
Concrete benefits in daily driving and sporty driving
The contribution of this technology is tangible in numerous driving situations:
- Urban driving and parking: This is where the advantage is most obvious. The number of lock-to-lock steering wheel turns is significantly reduced (dropping, for example, from 3 to less than 2 turns). Parallel parking and parking garage maneuvers become child's play.
- Highway stability: The car feels glued to its trajectory. The "slower" steering at high speed filters out minor vibrations and involuntary driver movements, reducing fatigue and increasing the sense of security on long journeys.
- Performance and driving pleasure: On winding roads, and often coupled with a drive mode selector (Sport Mode), the steering can adopt a very direct ratio for maximum responsiveness. The car feels more agile and connected to the road, delivering more intense driving dynamics.
- Active safety: Variable steering is an essential link in modern safety systems. In the event of a skid detected by the ESP (Electronic Stability Program), the system can autonomously apply a counter-steering micro-input, faster and more precisely than a human could, thereby helping to stabilize the vehicle even before the driver reacts.
It is important not to confuse it with simple power steering, whose role is solely to reduce the physical effort required to turn the steering wheel, without modifying the steering ratio. Variable ratio steering is an additional layer of technology. It is also complementary to the rear-wheel steering system (four-wheel steering), which acts on the rear wheels to further improve low-speed agility and high-speed stability. The combination of these two technologies represents the pinnacle of modern chassis engineering.
Compatible brands
Finitions équipées
42 finition(s) proposent cet équipement
Škoda Škoda Fabia
Active (Fabia III) (2015-2018)
Škoda Škoda Yeti
Active (1st generation - facelifted phase 2) (2013-2017)
Associated equipment
Drive Mode Selector
The drive mode selector is an electronic system that allows the driver to modify several dynamic vehicle parameters in real time to adapt its behavior to their preferences or road conditions. By operating a control, often a dial or a button on the center console, the driver can choose between various preconfigured profiles such as 'Eco', 'Comfort', 'Normal', 'Sport', or even a customizable 'Individual' mode. Each mode adjusts a combination of settings including throttle response, automatic transmission shift patterns, steering assist level, adaptive suspension firmness, and sometimes even the exhaust sound or all-wheel-drive management. This technology turns one car into several, offering remarkable versatility. It can behave as a smooth, fuel-efficient sedan for daily commutes, and then transform into a responsive and engaging sports car on a winding road. Increasingly widespread, this equipment has become a major selling point, symbolizing the personalization of the driving experience in the digital age.
ESP
ESP, or Electronic Stability Program, is an essential active safety system in modern vehicles, also known as Electronic Stability Control. Its primary role is to keep the vehicle on the trajectory intended by the driver, by preventing loss of grip and skidding. To do this, the ESP uses a series of sensors (wheel speed, steering wheel angle, lateral acceleration, yaw) that continuously analyze the consistency between the direction desired by the driver and the actual behavior of the car. If a discrepancy is detected, signaling the onset of understeer (the front wheels skid) or oversteer (the rear wheels skid), the system intervenes in a fraction of a second. It independently brakes one or more wheels and can also reduce engine power to bring the vehicle back onto the correct trajectory. Mandatory on all new vehicles sold in Europe since 2014, ESP is an electronic guardian angel that significantly increases safety during emergency avoidance maneuvers, in tight corners, or on slippery surfaces (rain, snow, ice). It works in synergy with other aids such as ABS and ASR (traction control).
Adaptive suspension
Adaptive suspension, also known as active damping, is an advanced chassis technology that adjusts damper firmness in real time. Using a network of sensors that continuously analyze the road surface (road quality), driving style (acceleration, braking), and vehicle movements (roll, pitch), an electronic control unit (ECU) modulates damper response within milliseconds. This modulation is achieved via electromagnetic valves or a magnetorheological fluid whose viscosity changes under the effect of a magnetic field. Unlike a conventional passive suspension, this intelligent system offers exceptional versatility. It can provide a soft damping setting for maximum comfort on the highway or rough roads, and then instantly firm up to ensure precise and reassuring road-holding during dynamic driving or emergency maneuvers. Having become a benchmark in the premium and sports segments, it is offered under various commercial names such as DCC (Volkswagen), PASM (Porsche), or Adaptive M Suspension (BMW), embodying the ultimate compromise between comfort and performance.
Variable Ratio Steering
Variable ratio steering, also known as active or dynamic steering, is a sophisticated chassis system that continuously optimizes the ratio between the steering wheel movement and the steering angle of the wheels. Unlike a standard steering system where this ratio is fixed, this technology adjusts it based on vehicle speed, the selected driving mode, and sometimes even the yaw rate. At low speeds, for city maneuvers or parking, the system makes the steering very direct: a small turn of the steering wheel results in a large wheel angle, which greatly facilitates maneuvers and reduces driver fatigue. Conversely, at high speeds on the highway, the steering becomes more indirect. A larger steering wheel movement is then required for the same steering angle, ensuring excellent straight-line stability, filtering out unintentional micro-corrections, and providing an enhanced sense of security. Controlled by an electronic control unit (ECU), this system uses an electric actuator, often coupled with a planetary gear set on the steering column, to add or subtract steering angle relative to the driver's input. It is a key component linking performance, comfort, and active safety.
Rear-wheel steering
Rear-wheel steering, also known as a four-wheel steering system, is an advanced chassis technology that allows a vehicle's rear wheels to pivot by a few degrees. Unlike a traditional fixed rear axle, this system uses electromechanical actuators to adjust the rear wheel angle based on vehicle speed and front wheel steering angle. At low speeds, typically below 60-80 km/h, the rear wheels turn in the opposite direction to the front wheels. This counter-steering virtually reduces the vehicle's wheelbase, thereby significantly decreasing the turning radius and improving agility for city maneuvers and parking. At high speeds, the rear wheels turn in the same direction as the front wheels. This parallel steering virtually increases the wheelbase, resulting in enhanced stability during highway lane changes and better handling in fast corners. Managed by a central ECU, this system continuously optimizes vehicle behavior to offer an ideal compromise between maneuverability and safety.